Anthracyclines are a large group of compounds synthesized by different Streptomyces species. They possess antibiotic activity and have cytotoxic effects on eukaryotic cells. All anthracyclines have a tetrahydronaphthacenedione ring structure attached by a glycosidic linkage to a sugar molecule, structural diversity of anthracyclines is generated by modifications of the backbone including a large number of different side chains.
Anthracyclines have excellent antineoplastic activity in metastatic, neoadjuvant, and adjuvant settings and are used in the treatment of various haematopoietic and solid tumours. Commonly used anthracyclines include but are not limited to mitoxantrone, doxorubicin, aclarubicin, daunorubicin, epirubicin and idarubicin. Although their mechanism of chemotherapeutic action is unclear involves noncovalent DNA intercalation, formation of covalent DNA adducts, topoisomerase II (topo II) poisoning, and free radical effects on cellular membranes and DNA. However, the clinical utility of anthracyclines are limited due to acute and chronic toxicities, particularly cardiotoxicity, myelosuppression, nausea and vomiting, and alopecia.
Heart failure following anthracycline therapy is a major clinical problem in cancer treatment. The establishment of predictors of the anthracycline treatment outcome would allow the identification and exclusion of individuals who would not benefit from said treatment, and thus to increase the safety of anthracycline treatment. Furthermore by determining which patients would benefit from Anthracycline treatment, but wherein said predicted outcome is suboptimal patients can be recommended for further chemotherapeutic or other treatments. Conversely by determining which patients would be adequately treated by anthracycline treatment alone the over-treatment of patients can be prevented. Accordingly there is a longfelt need in the art for determining which patients will benefit from Anthracycline treatment.
Methylation of the gene Topo IIalpha gene was recently observed in the cell line K562/MX2, which displays resistance to the anthracyclines KRN 8602 (MX2), etoposide and doxorubicin (Asano et al. Br J. Cancer. 2005 Apr. 25; 92(8):1486-92.). Sensitivity to the drug was restored by treatment with the demethylating agent 5-Aza-2′-deoxycytidine, thereby implying that Topo IIalpha methylation is a mechanism of drug resistance. The person skilled in the art when considering WO 2004/035803 in light of Asano et al. would not have a reasonable expectation of success that a methylation marker indicative of response to treatment targeting a hormone pathway would be a predictor of response to a treatment with an unrelated mechanism of action.
The present invention provides a novel method for predicting the outcome of anthracycline treatment of a patient with a haematopoetic or solid tumour by determining the CpG methylation status of at least one gene selected from the group consisting of PITX2; TFF1 and PLAU and predicting therefrom the outcome of anthracycline treatment.
The technical differences between the state of the art and the present invention are that the present invention provides a means for the prediction of anthracycline treatment by means of analysis of the methylation of at least one gene selected from the group consisting of PITX2; TFF1 and PLAU. The technical effect of this is to provide a predictor of treatment outcome specific to haematopoeitic or solid tumour treatment, as opposed to other treatments that may be treated by means of anthracyclines.
Thus, the objective technical problem solved by the method of the present invention is to predict outcome of anthracycline treatment of haematopoietic and solid tumours.
Prior Art in Methylation Analysis
5-methylcytosine is the most frequent covalent base modification in the DNA of eukaryotic cells. Methylation of DNA can play an important role in the control of gene expression in mammalian cells. It plays a role, for example, in the regulation of the transcription, in genetic imprinting, and in tumorigenesis. DNA methyltransferases are involved in DNA methylation and catalyze the transfer of a methyl group from S-adenosylmethionine to cytosine residues to form 5-methylcytosine, a modified base that is found mostly at CpG sites in the genome. The presence of methylated CpG islands in the promoter region of genes can suppress their expression. This process may be due to the presence of 5-methylcytosine, which apparently interferes with the binding of transcription factors or other DNA-binding proteins to block transcription. In different types of tumors, aberrant or accidental methylation of CpG islands in the promoter region has been observed for many cancer-related genes, resulting in the silencing of their expression. Such genes include tumor suppressor genes, genes that suppress metastasis and angiogenesis, and genes that repair DNA (Momparler and Bovenzi (2000) J. Cell Physiol. 183:145-54). Therefore, the identification of 5-methylcytosine as a component of genetic information is of considerable interest. However, 5-methylcytosine positions cannot be identified by sequencing since 5-methylcytosine has the same base pairing behaviour as cytosine. Moreover, the epigenetic information carried by 5-methylcytosine is completely lost during PCR amplification.